ROTATE-ABLE SOLAR PANELS?
WHY YOU SHOULD MAKE THE TRANSITION
If you’re preparing to buy a solar panel, this guide provides very valuable information on why you should choose rotate-able solar panels. Instead of the star component of a system installation – the solar panels.
Before we delve into the wonderful world of PV modules and which are the best solar panels to choose – we need to make sure we are talking about the right product. So let’s get any confusion out of the way for starters. The information on this website is focused on photovoltaic solar panels; also known as “solar PV” or “solar electricity” modules.
There’s another type of solar panel used for heating water (as opposed to generating electricity). This type is called a “solar hot water panel” or “solar thermal collector” and is a completely different beast.
Here’s an example of a roof with both types of panels on it:
INTENSITY AND ANGLE
When the sun is overhead, its rays are the most direct and intense.
As it becomes lower in the sky, the same area of light from the sun covers a larger area of the Earth.
As the area increases, intensity decreases; a solar panel receiving this light produces less electricity.
To partially compensate for the reduced intensity, a solar panel can be tilted to match the sun’s angle, although the complexity and upkeep of mechanical tracking systems add considerable cost to a solar energy installation.
TIME OF DAY AND SEASONS
During the day, the sun’s rays are most intense at noon
Weakest at dawn and dusk, and in between at other daytime hours
Other factors such as cloud cover being equal, a solar panel’s output is greatest at noon because the sun’s rays are more direct than at other times.
Seasons also affect the sun’s location in the sky. Because the Earth’s axis is tilted at 23.5 degrees with respect to the sun, the seasons change as the planet moves through its year long orbit.
In the summer, the Northern Hemisphere is tilted toward the sun and receives the most direct rays;
During the northern winter, the Southern Hemisphere gets more sunlight. Because the sun is more directly overhead in summer months, a solar panel puts out more power than during the winter, when the sun’s rays are less intense.
LATITUDE IS A FACTOR
At the equator, the sun’s rays are the most direct on Earth.
As you move toward the poles, the sun’s angle in the sky decreases, as does solar intensity.
The weakness of sunlight accounts for the extreme cold conditions near the poles.
According to NASA, the sun’s rays are 40 percent as intense there as they are at the equator.
The closer a solar panel’s location is to the equator, the greater will be its electrical output.
THE ROLE OF DISTANCE
The distance of the sun to an earthbound solar panel changes very little during the course of a year, as the Earth’s orbit is nearly a perfect circle.
However, distance plays a major role for the solar panels that power satellites and missions to space.
Although some space crafts can use solar panels, past the orbits of Neptune and Uranus, sunlight is too weak to be a practical power source.
Missions very far from the sun use atomic batteries that produce electricity for decades without the need for sunlight.
WHAT’S THE BEST ANGLE FOR MY SOLAR PANELS?
The angle of your solar panel is an important factor in maximizing your energy production. Depending on where you live, the best angle at which you should install solar panels will change. This is because it’s based on the average position of the sun over your property.
WHY DOES THE ANGLE OF A SOLAR PANEL MATTER?
Solar panels produce electricity when sunlight hits their surface, and they produce the most energy when that sunlight is exactly perpendicular to the panel face.
Therefore, the best angle for your solar panels is the one that allows the panels to get the most direct, perpendicular light.
While the sun is in a higher position in the sky during the summer and lower position during the winter, it has an average position right in between the two seasons.
By tilting your solar panels the same angle as the latitude of your home (which means pointing your panels at that average position), you are ensuring that you will get the maximum average output from your solar system throughout the year.
OTHER FACTORS AFFECTING SOLAR PANEL ANGLE
Your latitude isn’t the only factor in determining what angle your solar panels should be at. Here are a few things to consider when determining the best tilt for a solar array:
1. EXISTING ROOF DESIGN
It would be great if everyone had a roof that was angled exactly the same as their latitude, but every property is unique. Many roofs are going to have slopes between 30 and 40 degrees, which means that solar panels can lie flush against the roof and produce enough electricity for attractive returns.
If you are trying to install solar panels on a steep roof, it may not be possible to place panels at the optimal tilt with traditional racking systems.
Because the steep angle of your roof might already be higher than the optimal angle for production, the best you can do is lie your panels flat against the roof.
Low angle roofs will also face obstacles when it comes to solar panel installation and may require specialized racking if you’re looking to tilt them at the optimal angle.
Placing panels flush against these types of roofs will mean less electricity production, which will lead to reduced solar savings over time.
In the case of a flat roof, solar installers will usually opt to use racking systems that mount your panels up at an optimal angle.
While this allows for your panels to face the sun more directly, you may be limited when it comes to your system size.
Tilting panels up on a flat roof will lead to the panels shading one another unless you space and stagger the rows of panels out on the roof.
As a result, you can’t install as many panels as you would otherwise be able to if the solar panels were flush against the surface.
Regardless of whether your roof is steep or flat, it’s always best to have a professional solar installer mount the panels on your roof to ensure optimal production and optimal safety.
2. WINTER WEATHER
Solar panels work well in the winter, but you will typically see a dip in total energy production during particularly bad winters due to snow covering your panels and reducing their power output.
One way to counteract winter production dips is to install your panels at a lower angle than your latitude.
By doing this, you are setting up your panels to perform more efficiently in the winter because they will more directly face the sun as it shines from a lower point in the sky.
However, installing panels at angles of around 15 degrees or less can backfire, as snow won’t easily fall off of your panels. This will lead to long-lasting snow cover and decreased electricity production.
3. ORIENTATION OF THE PANELS
While the angle of your solar panels is important, a more important factor in your energy production is going to be the direction your panels face.
For the best results, solar panels should be oriented towards the east.
This is because the sun is always in the eastern half of the sky in the southern hemisphere.
You can still have an effective solar installation with arrays facing south or north but may need to install a larger system to meet the same amount of electricity production that a eastern panel would have.
It’s not a good idea to install your panels to face a suboptimal direction even if it means the best tilt possible.
CALCULATING SUN ANGLES
The angle of the sun in the sky at noon can be easily calculated for the solstices and equinoxes as follows:
Equinox = 90° - latitude
Summer solstice = Equinox + 23.5°
Winter solstice = Equinox - 23.5°
The diagram for Darwin below shows why southern façades (A façade, is usually one exterior side of a building, which is usually the front side) must be shaded in tropical locations to keep out the summer sun.
WHAT ABOUT SOLAR TRACKERS?
The sun’s position is constantly moving throughout the year, and the only way to always have your solar panels angled perfectly is to install a solar tracking system.
Solar trackers follow the sun as it moves slightly, which will bump up your energy production. If you are considering a ground-mounted solar system a solar tracking setup may work.
For the majority of solar shoppers, a rooftop system is the lowest cost and doesn’t take up space on the ground, and solar trackers can’t easily be installed.
Solar trackers are generally only used in commercial solar projects that can dramatically increase production with a tracking system.